1. Field of the Invention
The present invention relates to plug for a universal serial bus (hereinafter abbreviated as “USB”) connector (hereinafter abbreviated as “plug”), and a connector assembly using the plug, and in particular relates to the structure of a Standard-A plug or a Standard-B plug in the USB 3.0 standard.
2. Description of the Related Art
A USB connector is a type of connector that is used for the connection of electronic devices including personal computers and peripheral devices, and is widely used due to having the advantages of easy connection to a device, plug-and-play or hot plugging capability, and capability of being used as a terminal for power supply (refer to Japanese Unexamined Patent Application, First Publication No. 2001-217026, Published Japanese Translation No. 2008-508694 of the PCT International Publication, Japanese Utility Model (Registered) Publication No. 3059768, and http://www.hirose.co.jp/catalogj_hp/j24000019). The specification of the plug that constitutes a USB connector and the receptacle into which the plug is inserted are defined by standards.
On the other hand, in connecting a plug and cable to form a USB connector assembly, the structure of the connection portion is not particularly specified. For example, as shown in FIG. 7, a structure is employed in which a plug 1 is housed in a metal connector shell 2, a jacket 3a of a cable 3 is fixed in a grasping manner in a clamp portion 2a that is provided at the base end portion of the connector shell 2, and a plurality of electrical wires 3b that extend from the distal end of the jacket 3a to the distal end side are connected to a plurality of electrodes 1a arranged at the base end portion of the plug 1. Also, in the case of the cable 3 used for the USB 3.0 standard, the aforementioned plurality of wires 3b consist of two pairs of signal lines for the USB 3.0 standard that are shielded, one pair of wires for the USB 2.0 standard that are not shielded, a power line and a ground line, for a total of eight wires (only five are shown in the figure). Note that in the following disclosure, unless otherwise noted, the left side in the figures (the side to be inserted into a receptacle) shall be defined as the distal end side, and the right side (the side connected to the cable) as the base end side.
In the aforementioned cable 3, the plurality of wires 3b are covered from the outer side by a jacket 3a and a braid 3c. Accordingly, during the connection described above, work called “leading” is required to remove the jacket 3a and the braid 3c to enable connection of the wires 3b to the electrode 1a of the plug 1. In the aforementioned conventional connector assembly, the distance between the location where the jacket 3a and the braid 3c of the cable 3, that is fixed to the clamp portion 2a, are removed by leading, and each electrode 1a of the USB plug 1 (the distance shown by the letter D in FIG. 7) is substantially equivalent. Accordingly, the lengths of the plurality of (exposed) wires 3b that extend from the distal end of the jacket 3a and the braid 3c to the distal end side by leading are substantially equivalent.
However, when the lengths of the plurality of wires 3b in the aforementioned exposed portion are equivalent, in the signal wires for the USB 2.0 standard in which the periphery is not particularly shielded, since the surrounding shield by the braid 3c is eliminated, they become more susceptible to external noise. In addition, since the braid 3c is eliminated, there is also the problem of the region in which impedance mismatching between the paired signal wires for the USB 2.0 standard occurs expanding. Note that FIG. 7 shows the example of a Standard-A plug in the USB 3.0 standard, but even in the Standard-B plug in the USB 3.0 standard, a similar problem occurs.
The present invention was achieved in view of the aforementioned circumstances, and the object thereof is to provide a plug for a universal serial bus connector and a connector assembly that, in a plug for a USB connector and a connector assembly using the plug, can reduce the effects of external noise that the signal wires for the USB 2.0 standard receive and impedance mismatching between the paired signal wires for the USB 2.0 standard.